1. Technical Field
The present invention relates to a communication apparatus for used in an articulated robot and In particular, to a communication apparatus that uses a serial transmission line to transmit control signals necessary for controlling movements of the robotic apparatus.
2. Related Art
Articulated robots have now been used in many fields including various factories. In most cases, an articulate robot is provided with a robot main body including servo motors serving as a drive source of each joint and drivers serving as joint control devices. The drivers are used to drive the servo motors. Each joint control device is connected to a controller arranged outside of the robot main body via a signal line. A control signal is provided to each joint control device from the controller.
In a robot main body such as this, when each joint control device and the controller are separately connected by signal lines, a number of signal lines passing through the robot main body increases significantly. Therefore, the controller and each joint control device are connected by a serial transmission line. Control signals are transmitted from the controller to each joint control device through specification of an address (identification [ID]).
Although the invention is not a robotic apparatus, a numerically controlled machine tool disclosed in Japanese Patent Laid-open Publication No. 2001-222308 has an NC unit, a plurality of controlling sections, a remote Input/output (I/O), and an operating board connected by a serial transmission line. The NC unit transmits data. The controlling sections control a plurality of servo motors and a main axis motor. The remote I/O inputs and outputs data into and from the NC unit.
A hand is attached to a tip section of the robot main body. The hand grips (clamps) a workpiece and releases (unclamps) the grip by a drive source, such as a pneumatic cylinder. The controller also provides a control signal to a controlling section (hand control device) that controls the drive source of the hand. Gripping and releasing of the work is performed at appropriate timings.
However, the type of hand and the drive source to be used for the hand are selected by a user depending on the work. Therefore, at shipment of the robotic apparatus, the hand control device is not yet attached to the robot main body. Thus, a separate signal line for the hand control device is laid out in the robot main body, and the user connects the signal line for the hand and the hand control device.
However, in the above-described conventional configuration, in addition to the signal lines for the plurality of joint control devices, a dedicated signal line for the hand control device is required. Further reduction of the number of signal lines is difficult.